Approximately 38% of patients with AIDS develop CMV retinitis, a blinding viral infection of the retina. The drugs that are currently approved have to be given intravenously and have not been virucidal and progression of the retinitis ultimately ensues. There is a need for a systemic anti-CMV drug that can be given orally and that is effective for the treatment of active CMV retinitis. Lobucavir may be such a drug. Therefore, the purpose of the Lobucavir Peripheral CMV Retinitis Trial is to evaluate the safety and efficacy of lobucavir in the treatment of CMV retinitis in patients with AIDS.